A bone fracture may cause bone density losses throughout the body, not just close to the fracture site, and primarily around the time the fracture occurred, according to two studies from the University of California – Davis Health System.
“We know one fracture seems to lead to others, but we haven’t known why,” says Blaine Christiansen, associate professor of orthopaedic surgery at UC Davis, who led both studies. “Our work is the first step on the path to identifying the cellular mechanisms of systemic bone loss.”
The first study, published in Osteoporosis International, was based on about 4,000 participants in the Study of Osteoporotic Fractures, an observational study of older women that included hip bone mineral density (BMD) measures and fracture history gathered regularly over 20 years.
Outcomes showed that hip BMD decreased over time for all women in the study, but was greatest for those who had fractured a bone—even if the fracture was not near the hip. BMD reductions averaged between .89 and .77 percent per year for those with fractures, and .66 percent per year for those with no fractures. Those losses were greatest within the first two years of a break, explains a media release from University of California – Davis Health System.
The second study, published in the Journal of Bone and Mineral Research, was conducted using mice with femur fractures and BMD tests in various bones. Once again, bone loss occurred throughout the body, most notably in the spine, and was greatest within the first 2 weeks of fracture. It also was accompanied by higher levels of inflammatory markers in the blood.
Outcomes of the second study showed interesting age-related recovery differences as well. Younger mice eventually recovered their pre-fracture BMD levels, while older mice did not.
Christiansen notes in the release that he hopes to further characterize the post-fracture inflammatory factors that may contribute to bone loss following fracture.
“It’s possible that these factors are key to initiating BMD loss once a bone is broken,” Christiansen adds. “Ultimately, we hope to develop therapeutic strategies that interrupt those processes and prevent bone loss.”
[Source(s): University of California – Davis Health System, Science Daily]